Helicobacter pylori is a gastric pathogen of humans, and its persistence in the gastric mucosa has been in part attributed to its ability to counteract the host defense. The bacterium's marked ability to repair its oxidized macromolecules, including its DNA is one factor facilitating Helicobacter survival. The H. pylori MutS protein appears to play multiple and unique roles in DNA recognition, repair, and in recombination. However, the molecular mechanisms underlying the enzymes diverse functions are not understood, nor have its interacting partner proteins been identified. The goal here is to begin to understand the MutS repair function on a molecular level via enzyme assays, site-specific mutagenesis, and protein-protein interaction approaches. PUBLIC HEALTH RELEVANCE: The project involves characterization of factors used by a prevalent human pathogen to enable its survival in humans. The long term goal is to be able to thwart the ability of the bacterium to resist the defense mechanisms mounted by the host.